CN112385097B

CN112385097B - System for transferring electric power between a rotating element and a stationary element

Info

Publication number: CN112385097B
Application number: CN201980045558.2A
Authority: CN
Inventors: 若弗鲁瓦·贝拉尔; 拉迪·拉姆拉尔; 奥列弗·伯纳德
Original assignee: Mersen France Amiens SAS
Current assignee: Mersen France Amiens SAS
Priority date: 2018-07-10
Filing date: 2019-07-08
Publication date: 2024-01-09
Anticipated expiration: 2039-07-08
Also published as: FR3083924B1; US20210135417A1; CN112385097A; CA3104214A1; BR112020026443A2; FR3083924A1; EP3821504A1; US11569625B2; WO2020012099A1

Abstract

A system for transferring electrical current between a rotating element and a stationary element, comprising: -a support (10) of general shape in sheet form, comprising a conductive portion (11) electrically connected to the fixing element; -a brush holder (20) mounted on the support (10) and supporting a brush (30) urged into contact against the rotating element; -electrical connection means (42) for connecting the conductive portion (11) of the support to a cable (40) joined to the brush (30), wherein the resistive element (12) is located between the brush (30) and the conductive portion (11) of the support (10) and prevents the current from flowing directly between the conductive portion and the brush.

Description

System for transferring electric power between a rotating element and a stationary element

The present invention relates to the transfer of electric current between a rotating element and a stationary element, the rotating element being moved in a rotational movement relative to the stationary element.

The invention can be used for example in rotating electrical machines, in particular in asynchronous machines and more particularly in generators for wind turbines, or in industry (cement plants, ports, mines …).

The invention can be used, for example, in the case of a power transfer of more than 25kW, for example between 25kW and 100kW (except for the latter values), or equal to 100kW, or strictly more than 100kW, advantageously more than 500kW (in particular in the wind power industry).

The invention is in no way limited to use in the wind power industry: for example, the invention may be used in synchronous motors for power transfer, as well as in various fields, such as in the processing industry (chemical industry, paper making, etc.), aviation, aerospace, robotics, power production, or others.

The rotating element may be a rotor, a rotating shaft, a ring mounted on the rotating shaft, a slip ring or other.

The fixing element may be a stator, a fixing coil, a fixing device of a flexible member electrically connected to the carbon brush, or others.

Typically, a carbon brush (english "carbon brush") or a fiber brush (also english "fiber brush") is mounted on a fixed grip frame (english also called "reel") via a brush holder and pressed against a rotating element, so that it is possible to ensure the transmission of electric current between the rotating element and flexible members connected to the carbon brush or the fiber brush, which are electrically connected to the fixed element.

It is known to use not only the grip frame as a mechanical support, but also to transmit current to or from the element against which the carbon brush is pushed. Thus, the facility benefits in terms of simplicity.

However, the manner in which the transfer of current takes place effectively between the element against which the carbon brush is pushed and the holder is relatively difficult to monitor. In particular, it is difficult to detect a breakage of the flexible member connected to the carbon brush, which may be problematic in case the environment is not easily accessible, such as a wind turbine.

Thus, there is a need for a system that enables better monitoring that would enable particularly advantageous detection of faults.

A current transfer system between a rotating element and a stationary element is proposed, the rotating element being moved in a rotational movement relative to the stationary element, said transfer system comprising

A support, having an overall shape of a plate, on the periphery of the rotation axis of the rotating element, comprising a conductive portion electrically connected to one of the fixed element and the rotating element,

at least one and advantageously several brush holders mounted on and supported by or integrated on the support and shaped to hold at least one conductive sliding contact element intended to be pushed into contact against the other of the fixed element and the rotating element,

a resistive element located between the conductive sliding contact element and the conductive portion of the support when the conductive sliding contact element held by the brush holder is urged into contact to limit the passage of current directly between the conductive portion, such as the conductive plate, and the conductive sliding contact element,

-electrical connection means for electrically connecting the conductive portion of the support to a flexible member rigidly connected to the conductive sliding contact element for conducting an electrical current between the conductive portion and the conductive sliding contact element.

The resistance of the resistive element may be greater than or equal to the resistance of the conductive sliding contact element.

The system may comprise said conductive sliding contact element supported by the brush holder and intended to be pushed into contact, but it will be appreciated that it may be marketed without carbon brushes.

The resistance of a conductive sliding contact element may be measured between an end intended to be in contact with the other of the fixed element and the rotating element (e.g., a contact surface) and an end opposite the end (e.g., a terminal). The definition of the resistance of the carbon brush can be found in standard CEI 60136.

For example, the resistive element may have a resistance of at least 0.3 ohms, advantageously at least 0.5 ohms, advantageously at least 1 ohm, advantageously at least 100 ohms, advantageously at least 1 kilo ohm.

The arrangement may be such that when the conductive sliding contact element is mounted such that it is urged against the other element (e.g. the rotating element), the total or quasi-total amount (e.g. more than 95% of the strength) of current flowing between the contact element and the other element is passed through the means for electrically connecting, e.g. one or more flexible members rigidly connected to the contact element. In other words, the resistive element forces a path for the current transfer.

Thus, even in the case of alternating or non-constant current, monitoring of the transfer of current between the rotating element and the stationary element can be made simpler as long as the hypothetical path of the current has been determined.

For example, when several conductive sliding contact elements are provided, such a system may enable to facilitate detection of an imbalance in current intensity from one conductive sliding contact element to another.

Furthermore, in case of a rupture of the flexible member, no current passes through the affected conductive sliding contact element (e.g. carbon brush) anymore, thus avoiding operation in a degenerate mode in which current will pass from the conductive part to the carbon brush through the wall of the carbon brush (e.g. via the brush holder).

Surprisingly, even with a relatively low electrical resistance (about 1 ohm), the total or quasi-total amount of current (e.g. more than 95% of the strength) flowing between the conductive sliding contact element and the further element is achieved by a flexible member rigidly connected to the conductive sliding contact element even after a relatively long use time, e.g. in the order of a few months.

For example, when the conductive sliding contact element is supported by the brush holder and urged into contact, the resistive element may include an insulating element between the conductive sliding contact element and the conductive portion of the support. The system may be shaped such that the insulating element thus prevents current from passing directly between the conductive portion and the conductive sliding contact element.

The insulating element has a resistance of at least 100 kilo-ohms.

In one embodiment, the resistive element may be different from the support and from the brush holder. The different elements may be fastened to the support and/or the brush holder, for example.

The resistive element may be, for example, part of or comprise a brush holder.

Advantageously, the insulating element, and more generally the resistive element, may be part of a support having the overall shape of a plate. The support may therefore also comprise a resistive portion, advantageously an insulating portion. Thus, the resistive element (advantageously insulated) comprises the resistive (advantageously insulated) portion.

In one embodiment, for example, a resistive (advantageously insulating) material may be applied to the brush holder and/or to the conductive portion of the support.

The resistive or insulating material may also enable protection of the brush holder and/or support.

The resistive (advantageously insulating) material may be an insulating coating, such as an anti-flash paint, plastic or other. The resistivity of the material may be at least 0.1 ohm-meter, advantageously at least 1 ohm-meter, advantageously at least 10 ³ Ohm-meter.

Advantageously, the resistive (advantageously insulating) material may be chosen such that its resistivity varies by less than 1% when subjected to voltages between 600V and 1000V and advantageously even for voltages between 230V and 2700V.

The brush holder may, for example, be made of, or at least partially coated with, a resistive material (advantageously an insulating material), such as a polymer. In the latter case, a brush holder made by stretching a metal sheet covered with an insulating material may be provided.

In the case of a resistive element as part of the support, one of the conductive and resistive (advantageously insulating) portions can be obtained by applying a conductive or corresponding resistive (advantageously insulating) material to or onto the other of the resistive element and conductive portion.

Thus, the resistive portion may enable protection of the conductive portion at least for surfaces and/or edges of the conductive portion covered by the resistive material, which may be of interest in case of aggressive environments.

The support, which is plate-like in overall shape, may advantageously be non-convex, e.g. defining several straight segments and forming an angle between them, to at least partly enclose the rotating element or others.

Advantageously, the support, which has the overall shape of a plate, may be circular-arc-shaped.

The support may extend over 20 °, 60 °, 90 °, 180 ° or even 360 ° —in this case it is a closed grip frame.

The support may advantageously be arranged concentrically with the rotating element, that is to say the support defines a radial direction converging towards a point on or near the axis of rotation of the rotating element.

Alternatively, the support member having a plate-like overall shape may have a straight line profile from one end of the support member to the other end. For example, the support may have a rectangular or square shape.

The support may in particular have a thickness of more than 0.5 mm, for example from about 1 mm to 20 mm.

The conductive portion of the overall plate-like support may for example comprise a conductive plate.

In one embodiment, the conductive plate may advantageously occupy more than 90%, advantageously more than 95%, advantageously the entire surface of the support in the shape of a plate as a whole.

In this application, it is understood that the plate includes two surfaces and edges that are opposite each other and away from each other by the thickness of the plate. The thickness of the plate is much smaller than at least one of the dimensions of the surface, for example at least less than one tenth of the length of the surface. Under normal use conditions, these surfaces are in a direction perpendicular to the axis of rotation or a plane substantially perpendicular to this direction.

The conductive plate may be relatively robust and in particular have a thickness of more than 0.5 mm, for example about 1 mm to 20 mm, in particular in case the conductive part is made of copper, for example between 3 mm and 6 mm. This may also be referred to as a bus bar (or "bus bar").

The conductive plate may be, for example, arc-shaped and may extend over 20 °, 60 °, 90 °, 180 ° or even 360 ° —in this case it is a closed grip frame.

Alternatively, the conductive plate may have a rectangular, square shape, which may enable integration of other elements to be fastened in the machine, or even from the moment of design into a stationary part of the machine, for example.

For example, the support may or may not be integrated into the fixed part of the machine from the moment of design.

In another embodiment, the conductive plate may occupy less than 90%, in particular less than 70%, 60% or 50% of the surface of the overall plate-like shaped support.

In case the resistive element comprises a resistive portion as part of the support, the conductive plate may advantageously abut at least a portion of the resistive (advantageously insulating) portion, the portion having the shape of a plate such that at least the portion of the conductive plate and the resistive (advantageously insulating) portion are in contact via their thickness.

Thus, a resistive (advantageously insulating) material may be applied to the conductive plate to form the portion having the shape of the plate adjoining the conductive plate.

At least this portion of the resistive (advantageously insulating) portion may occupy more than 10%, advantageously more than 30%, 40% or 50% of the surface of the support.

The brush holder may for example be mounted on at least that part of the resistive (advantageously insulating) portion without being in direct electrical contact with the conductive portion. Thus, the insulating portion between the conductive sliding contact element and the conductive portion limits or prevents current from passing directly between the conductive portion and the conductive sliding contact element.

For example, the conductive plate may contact the (complementary) inner edge of the conductive plate in the shape of a circular arc on the outer periphery of at least this portion of the resistive (advantageously insulating) portion.

Advantageously, at least a portion of the resistive (advantageously insulating) portion may comprise a layer of resistive (advantageously insulating) material, known as a resistive (advantageously insulating) layer, applied to at least a portion of at least one surface of the conductive plate.

When the conductive sliding contact element is supported by the brush holder and urged into contact, the resistive (advantageously insulating) layer may extend, for example, at least in a plane sandwiched between the conductive plate and the conductive sliding contact element, so that the resistive (advantageously insulating) layer prevents current from passing directly between the conductive plate and the conductive sliding contact element.

The layer of resistive (advantageously insulating) material may or may not directly contact the surface of the conductive plate. For example, a spacer layer may be provided between the layer of resistive (advantageously insulating) material and the surface of the conductive plate.

The layer of resistive (advantageously insulating) material may or may not directly contact the wall of the element for sliding contact. In particular, the layer of resistive (advantageously insulating) material may be in contact with the brush holder, in particular if the brush holder defines a cage completely surrounding the carbon brush.

The layer of resistive and/or insulating material may advantageously cover more than 10%, advantageously more than 80%, and in particular all of at least one surface of the conductive plate.

A layer of resistive (advantageously insulating) material may be applied to at least a portion of only one of the two surfaces of the conductive plate, or may be applied to both surfaces.

A layer of resistive (advantageously insulating) material may cover both surfaces of the conductive plate.

The layer of resistive (advantageously insulating) material may or may not be relatively fine, particularly in the case of a resistive (advantageously insulating) material applied in a fluid state (e.g. via a brush or a nebulizer). The layer of resistive (advantageously insulating) material may in particular have a thickness greater than 10 micrometers, for example between 0.01 and 20 millimeters.

In one embodiment, for example, a resistive (advantageously insulating) layer may be overmolded or coated onto the conductive portion.

The conductive portion may be made of copper or other conductive material, for example. The conductive portion may comprise several layers of different conductive materials, e.g. a layer of copper and a layer of steel, to harmonize conductivity and robustness.

The resistive element may be made of graphite or other materials, for example.

The insulating element may for example be made of one or more insulating materials, for example of a polymer, in particular in the case of a conductive portion comprising a trace made of copper.

The conductive plate and/or the support may advantageously be flat in a plane comprising tangential and radial directions, perpendicular (or substantially perpendicular) to the rotation axis.

The conductive plate and/or the support (advantageously insulating) may be cut, for example, in the shape of a circular arc, molded or otherwise.

The support, which is plate-shaped as a whole, can be connected rigidly to the fixing element, for example.

The conductive sliding contact element may for example comprise a carbon brush, in which case a brush holder mounted on and supported by the support may be shaped to receive the carbon brush and urge the carbon brush into contact against the other of the fixed element and the moving element.

Carbon brushes may or may not typically include carbon, for example in the form of graphite.

For example, the carbon brush may be made of a material substantially including carbon and metal, for example, obtained by mixing carbon powder and metal powder. The metal may comprise silver, for example. Some or all of the silver may be replaced with copper or another metal.

The brush holder may for example comprise a spring element pushing the carbon brush towards the other element.

The present invention is in no way limited to contact carbon brushes. For example, the conductive sliding contact element may comprise a fiber brush in contact with a fiber or wire, such as a comb-like bundle of carbon fibers or otherwise. For example, a holder made of aluminum may be provided, which is divided into two parts, assembled to the stator, brush holders each fastened to the holder, and comb-shaped bundles made of carbon fibers mounted on the holder.

In the case of a contact fiber brush, the system may be devoid of a spring element for urging the contact element against the other of the stationary element and the rotating element. The brush holder may indeed be arranged close enough to the other element, and the fibers of the fiber brush may be long and stiff enough for the fibers themselves to push at least a portion of their ends against the other element.

Of course, a spring element may also be provided to push the contact fiber brush against the other element.

The resistive element enables creation of a more favourable environment for the installation of the sensor than a conducting part that can withstand strong and/or variable currents, thereby again enabling better management of the monitoring of the current transfer. In particular, the resistive (advantageously insulating) portion may enable limiting the contact between the sensor and the conductive portion.

The resistive element is sized to prevent any direct electrical contact between the face of the contact element and the conducting portion through which the current passes. For example, the resistive element (advantageously insulated) may cover all or more than 80% of the face of the conductive plate on which the contact element is mounted. According to another example, the resistive element has dimensions close to those of the contact element: for example, an insulating material may be applied to the conductive plate at the location of the contact elements.

According to a further example, the size of the resistive element (advantageously insulating) may be smaller than the size of the face of the contact element facing the face of the conductive plate, as long as the element is thick enough to prevent contact between the contact element and the conductive plate and the formation of an arc between the contact element and the conductive plate.

Advantageously, the resistive (advantageously insulating) material may be applied to or against the conductive portion (and to or against the brush holder, respectively) in a non-removable manner.

More generally, the resistive element (advantageously insulated) may not be separable from the conductive portion (and correspondingly from the brush holder) without degradation of the transmission system.

Advantageously, the transmission system may further comprise at least one sensor capable of measuring a parameter value representative of the operation of the conductive sliding contact element, such as a temperature, a current, a wear, an acceleration (for example by detecting abnormal vibrations) or other.

The sensor or sensors may enable detection of an imbalance or the like in which current does not pass in the flexure or from one contact element to another.

The sensor or sensors may enable detection of the flexible member breaking so that a decision (e.g. stopping use, maintenance, etc.) may be made after an alarm message is issued, thus enabling to avoid a small number of carbon brushes being overloaded.

The sensor or sensors may be mounted in or on the resistive element, advantageously in or on the insulating element. In the case of a resistive element obtained by applying a material in a fluid state, one or more sensors may be embedded in the material.

The sensor or sensors may be mounted, for example, in the resistive portion of the support and/or the resistive material of the brush holder.

In one embodiment, the system may further comprise at least two conductive linear elements (wires, traces, straps …) electrically connecting the sensor to the processing device to exchange measurements or commands.

In the case of sensors mounted on resistive elements fastened to or integrated into the brush holder, electrical connections may be provided between these sensors and cards mounted on the support, for example embedded in an insulating material forming the insulation of the support.

Alternatively or additionally, means for wireless transmission of data, such as bluetooth, zigBee or others, may be provided.

Advantageously and in a non-limiting manner, these conductive linear elements may be at least partially embedded in an insulating material.

Advantageously and in a non-limiting manner, these elements may be at least partially embedded in a resistive (advantageously insulating) portion. The presence of the resistive (advantageously insulating) portion is used to protect the conductive linear element.

In one embodiment, the system may also include a processing device, such as a microcontroller, microprocessor, or other.

Advantageously and in a non-limiting manner, these processing means may be at least partially embedded in a resistive (advantageously insulating) material, advantageously in an insulating portion. The presence of the insulating portion is utilized to protect the processing device.

Alternatively, the processing means may be installed on the system and/or remotely, e.g. accessible via a telecommunication network, such as a mobile telephone network or others.

Advantageously, these processing means may be arranged to control the delivery system. For example, the processing device may be in communication with an actuator, such as an actuator of a rotating element (e.g., a transmission), an actuator of a ventilation device (fan, exhaust fan, or the like), and/or the like.

The invention is in no way limited to controlling the transfer system by the processing means. For example, the control may be performed by a human operator-in which case, for example, data from measurements made by the sensors may be displayed on a screen or monitoring system such as SCADA (standing for "monitoring control and data acquisition") in the wind power industry.

Advantageously and in a non-limiting manner, a processing device arranged to control the transfer system may be in communication with the sensor.

Advantageously, the processing means may be arranged to control the transfer system in dependence of measured values from the sensors.

For example, the processing means may generate a message for controlling the rotating element, for example by controlling the torque, or for controlling the ventilation device by controlling its flow rate and/or the temperature of the circulating air, based on the received measured values.

In an advantageous embodiment, the processing means may be arranged to issue a message for controlling the ventilation device in case an imbalance of the collecting/injecting current from one conductive sliding contact element to the other conductive sliding contact element is detected.

The control information may be created to enhance cooling of the at least one conductive sliding contact element, for example by increasing the flow rate and/or by decreasing the temperature of the circulating air.

Such control may enable facilitating the transfer of current. In particular, by controlling the ventilation, the temperature can be adjusted. By reducing the temperature and/or by adjusting the flow rate of air to facilitate dissipation of heat in the transfer system, it may be desirable in some cases to at least partially rebalance the current from one contact element to another.

Ventilation may also enable cooling or limit heating of the rotating element.

Advantageously, the processing means may be arranged such that in case no transmission of current through the conductive sliding contact element is detected (e.g. a rupture of the corresponding flexible member is detected), a control message is created to increase cooling of at least the other conductive sliding contact element, e.g. to increase cooling of all conductive elements for sliding contact. Thus, the conductive sliding contact element can be limited from overheating and actually overloading in operation.

Advantageously, the processing means may be arranged such that in case an imbalance of collecting/injecting current from one conductive sliding contact element to another is detected while all conductive elements for sliding contact are transmitting current, a control message is created to at least increase the cooling of the conductive sliding contact element transmitting the majority of the current, thereby limiting the degradation related to overload of the conductive sliding contact element or elements.

In one embodiment, and in particular when a resistive or insulating material is applied to the plate and/or brush holder, the resistive (advantageously insulating) material may be deposited by deforming the material on the conductive plate and/or brush holder, said material advantageously having the shape of a layer already before deformation. The operation may be performed at a low temperature or at a temperature below the temperature at which the insulating material changes composition or phase.

Advantageously, the resistive element (advantageously insulated) may be coated and/or overmolded, glued to the conductive plate, for example by coating or potting (english "potting") around the conductive plate and/or brush holder, or its material may be applied to the plate and/or brush holder or others, for example with a brush, by a nebulizer or otherwise, when in a liquid, gaseous or powder state.

The material of the resistive (advantageously insulating) portion may be laminated to the conductive plate or applied manually or otherwise.

In one embodiment, the resistive (advantageously insulating) element may comprise a paint or varnish, for example comprising a resin such as an epoxy or other paint. This may be of interest in particular in the case of brush holders receiving several carbon brushes: varnish may be applied to the inner wall of the brush holder to insulate the carbon brushes from each other.

In one embodiment, the insulating material may comprise a thermoplastic polymer material, in particular a thermosetting polymer material.

For example, polyethylene naphthalate or PEN may be used, e.gAnd (3) a film.

In this case, the material may be heated to a temperature of, for example, 120 ℃ to deform the layer.

In one embodiment, the insulating material may comprise, for example, polyimide in the form of a film, for exampleFor example->And (3) a film.

In one embodiment, the polyimide film may be embedded in PEN.

Advantageously, all or part of the brush holder may be fastened to the support in a non-removable manner, that is to say, without degradation of the transmission system, the brush holder cannot be separated from the conductive plate. Thus, no adjustment need be provided to position the brush holder during installation of the bus bar.

For example, at least a portion of the brush holder may be secured by lamination in a resistive (advantageously insulating) portion.

In particular, the brush holder may be obtained from sheet metal, for example by folding and/or stretching. The end edges of the sheet are then laminated with a resistive (advantageously insulating) portion to secure the brush holder to the support.

In one embodiment, the brush holder may comprise two elements, which may be assembled to each other in a reversible manner, only one of these elements being fastened to the support in a non-removable manner.

For example, the brush holder may include:

a removable portion comprising at least a portion of a cage intended to receive a carbon brush,

an adapter portion, which is fastened to the support in a non-removable manner, for example to a resistive (advantageously insulating) portion.

Advantageously, the removable portion can be adjusted in a radial direction, thus enabling the positioning of the cage to be adapted with respect to the diameter of the rotating element. This may enable to facilitate compliance with the following recommendations: according to this proposal, the cage and the ring must be 2 to 3 mm apart.

Advantageously, a plug-set system may be provided for enabling the carbon brushes to be connected/disconnected when the machine is under load, in particular in the case of synchronous generators for hydroelectric power plants.

Advantageously, the non-removable portion fastened to the support may be partially embedded in a resistive (advantageously insulating) material.

An assembly comprising a rotating element, a stationary element and the above system for transferring data is also proposed. The assembly may or may not be integrated into the wind turbine.

The assembly may comprise several supports or a single support.

A wind turbine comprising the assembly is also presented. The rotary element may comprise a high speed shaft, rigidly connected to or driven in motion by the shaft.

The invention is used for power transfer via rotary contact, in particular transfer of high voltage of more than 100V, advantageously more than 400V, and/or transfer of high electric power of more than 0.1MW, advantageously more than 500kW (in particular in the wind power industry).

More generally, the invention can be used for power transfer of greater than or equal to 25kW, for example between 25kW and 100kW (the latter value being excluded (especially in industry)), equal to 100kW (especially in industry or in wind power industry), or strictly greater than 100kW (especially in wind power industry), for example greater than or equal to 200 kW.

Therefore, the above-mentioned assembly is proposed for use in industry, in particular in cement plants, ports, mines, etc., or in the wind power industry.

The invention is not limited to the transmission of continuous signals: for example, the transfer system may be used for grounding. For example, four systems may be provided, each having a bus bar type grip: three of these holders are used to deliver the corresponding phase, while the last holder is dedicated to delivering a ground signal that is generally empty (null) but subject to relatively unpredictable variations.

The connection means may comprise a pin or rod, a device with a screw and a bolt that mate with an aperture defined in the conductive plate and a terminal of the flexible member, a male connector or female connector intended to mate with a female connector or male connector, respectively, of the terminal of the flexible member, a protrusion in the plane of the conductive plate made integral with the conductive plate, or otherwise.

A method for manufacturing a current transfer system between a rotating element and a stationary element, the rotating element being moved in a rotational movement relative to the stationary element, is also proposed, the method comprising:

providing a support in the form of a plate of overall shape, which is intended to be located on the periphery of the axis of rotation of the rotating element, which support comprises a conductive portion intended to be electrically connected to one of the stationary element and the rotating element,

providing at least one brush holder mounted on or integrated into the support, the at least one brush holder being shaped to hold a conductive sliding contact element intended to be pushed into contact against the other of the stationary element and the rotary element,

Installing a conductive sliding contact element in the brush holder,

providing a resistive element between the conductive sliding contact element and the conductive portion of the support, the resistive element having a resistance greater than or equal to the resistance of the conductive sliding contact element,

-providing electrical connection means for electrically connecting the conductive part to a flexible member rigidly connected to the conductive sliding contact element for conducting a current transfer between the conductive plate and the conductive sliding contact element.

Of course, the invention is not limited by any order of the steps set forth above.

At least one of the support and the brush holder may advantageously comprise a resistive element, which is advantageously insulated and thus arranged between the conductive sliding contact element and the conductive portion of the support.

Alternatively, spring means, brush holders and/or the like may also be installed.

Advantageously and in a non-limiting manner, a resistive material, advantageously an insulating material, may also be applied to or against the conductive portion and/or brush holder to form a resistive (advantageously insulating) portion.

The step of applying a resistive material, advantageously an insulating material, may advantageously be performed by deforming the resistive or insulating material over all or part of at least one of the faces of the conductive plate and/or over the brush holder.

In one embodiment, the brush holder may be obtained from the sheet metal, for example by folding or stretching the sheet metal.

The brush holder may comprise a wall of the housing defining the carbon brush, for example three or four walls.

In one embodiment, the brush holder may comprise at least one fastening element extending from one of the walls of the brush holder towards the outside of the brush holder in a plane offset relative to the housing of the carbon brush, for example a fastening lug or protrusion from a sheet of metal, for example the same sheet of metal from which the brush holder is derived.

In one embodiment, the method may further comprise a step involving laminating the lugs into a resistive or insulating material of the resistive or insulating portion.

In another embodiment, the fastening tab may be pierced by the aperture, and the method may comprise a step involving fastening the tab to the support by screwing or equivalent.

The brush holder may be fully or partially conductive or fully or partially insulating.

The invention will be better described with reference to the following drawings, which show non-limiting embodiments given as examples.

Fig. 1 schematically shows a wind turbine according to an embodiment of the invention.

Fig. 2 shows an example of a transfer system of the type known in the prior art.

Fig. 3A is a schematic cross-sectional view of an example of a delivery system according to an embodiment of the present invention, wherein the insulating layer is relatively localized and the brush holder is reversibly threaded onto the insulating layer.

Fig. 3B is a schematic cross-sectional view of another example of a delivery system according to an embodiment of the present invention.

Fig. 3C is a schematic perspective view of yet another example of a delivery system according to an embodiment of the present invention.

Fig. 4 is a perspective view of an example of a transfer system according to an embodiment of the present invention, in which an insulating layer covers the entire conductive plate and brush holders laminated in the insulating layer, which is not shown in the figure.

Fig. 5 is a schematic cross-sectional view of an example of an assembly according to yet another embodiment of the invention.

Fig. 6A, 6B and 6C show alternative embodiments in which the sensor and the processing means are arranged on a conductive plate.

The same reference numbers may be used throughout the drawings to refer to the same or like elements in form or function.

Referring to FIG. 1, a wind turbine 100 includes a tower 101, a nacelle 112, and blades 102 rigidly connected to a "low speed" shaft 103.

Multiplier 104 enables conversion of the rotational motion of low-speed shaft 103 to faster motion of "high-speed" shaft 105.

The generator 115 enables the generation of electrical current from the motion of the high speed shaft 105.

The generator 115 is a rotary electric machine including a rotor, a stator, and carbon brushes. Which will be described in more detail with reference to fig. 3.

Fig. 2 shows an example of a generator of the type known in the prior art.

Referring to the figure, a conductive plate 201 having a circular arc shape is disposed around a rotation axis (D). These conductive plates are rigidly connected to a stator, not shown.

The brush holder 202 is fastened to the conductive plate 201. Each brush holder defines a cage that receives a carbon brush 230 and a spring means 203 for urging the carbon brush into contact against a ring of the rotating element 204 of the generator. The shaft of the rotor is not shown in fig. 2.

The other end of the flexible member 205, which is fastened to the carbon brush by one end, is connected to a connecting member 206 that is in electrical contact with the plate member 201.

However, the brush holders 202 themselves are conductive such that the generated current can flow from the carbon brush toward the corresponding plate 201 via the corresponding brush holder without passing through the flexible member 205.

Thus, breakage of the flexible member 205 may not be detected. Furthermore, an imbalance in the collection of current from one carbon brush to the other carbon brush may not be detected.

Referring to fig. 3A, a support in the shape of a plate 10 is provided in its overall shape, as seen in cross section. The support 10 comprises a conductive plate 11 of the busbar type and a layer 12 of insulating material is applied on a portion of the conductive plate 11.

The brush holder 20 is here fastened to the layer 12 with screws 21.

The brush holder 20 is made of sheet metal. The sheet is folded or stretched to define, with the insulating layer 12, a housing that receives the carbon brush 30.

A spring, not shown, enables the carbon brush 30 to be pushed in a direction perpendicular to the plane of the sheet, for example, toward the ring.

The carbon brushes are connected to the flexible member 40 in a manner known per se.

The flexible member 40 itself is connected to a terminal 41, which terminal 41 is fastened into the conductive plate 11 by a screw nut system 42.

It can be noted that a screw 21 for fastening the brush holder 20 to the insulating layer 12 is received in the aperture 18 through the conducting portion 11. An insert 17 made of insulating material covers the wall of the orifice 18: the carbon brush 30 is in contact with the conductive plate 11 only via the flexible member 40.

In the event that the screw is long enough so that a portion protrudes from the side opposite the brush holder side, the end of the screw may be covered with a washer, plug, or other type of insulating material.

Alternatively or additionally, the screw itself may be made of or covered with an insulating material. For example, PTFE (polytetrafluoroethylene) or others may be used.

The insulating material of the insert 17 may be, for example, a composite material of epoxy resin reinforced with glass fibers. The same or different materials may be selected for insulating layer 12.

The current collected by the carbon brush 30 thus reaches the conductive plate 11 via the flexible member 40.

In this example, the insulating layer may be made of, for example, a composite material of epoxy resin reinforced with glass fibers.

In an alternative embodiment, not shown, instead of the insulating layer 12, a resistive layer obtained, for example, by applying a paint on a portion of the surface of the plate 11 may be provided.

In this example, the insulating layer 12 extends over only a portion of the surface of the conductive plate 11, which corresponds to the position of the brush holder 20.

In the example of fig. 3B, the insulating material 12 is applied to the entire surface of the conductive plate 11 except for the contact posts 42'.

The brush holder 20 defines a cage with four sides and comprises two lugs 29 in a plane offset with respect to the position of the carbon brushes and embedded in the insulating material 12, which lugs are not in direct electrical contact with the conductive plate 11.

Thus, the insulating layer 12 is located between the graphite carbon brushes 30 and the conductive plate 11 and is shaped to prevent any passage of current between the carbon brushes 30 and the conductive plate 11 except via the flexible member 40 connected to the contact posts 42'.

In this fig. 3B, the spring means for pushing the carbon brush toward the rotary element are also not shown.

Referring to fig. 3C, the spring means is also not shown, but instead, it can be seen how the flexible member 40 is fastened to the carbon brush 30.

In this embodiment, the support 10 includes a conductive plate 11 having a circular arc shape abutting a part of the insulating portion 12. An insulating material is applied to the edge 13 of the conductive plate 11, thereby forming the insulating portion 12.

In this example, the brush holder is obtained by stretching the sheet and fastening the lugs 29 to the insulating portion 12 by any suitable means, for example by lamination, by gluing or otherwise.

The carbon brush 30 is in contact with the insulating material 12, which prevents any transfer of current between the carbon brush 30 and the conductive plate 11, except via a flexible member, not shown.

In an embodiment not shown, the support may comprise an insulating plate and a conductive portion comprising a trace made of a metal mounted on or embedded in the material of the insulating plate.

In the embodiment of fig. 4, a support 410 in the form of a plate of overall shape is provided, comprising a metal plate 411 of the busbar type, at least one face (visible in fig. 4) of the metal plate 411 being completely covered by the insulating material shown in this fig. 4.

The support 401 is concave at the sides of the rotor 404 so as to partly enclose the rotor.

The mounting bar 450 enables fastening of the support 410 to a not shown fixed part.

The electrical connection strip 451 enables to electrically connect the support 411 to an electrical power transmission flexible member (not shown) mounted on a fixed part of the nacelle.

Two brush holders 420 are non-removably secured to the support 410. These brush holders 420 each define a cage for receiving the carbon brushes 430, and further include a pressure system 450 for receiving a spring, not shown, that enables the corresponding carbon brush to be urged against the rotor 404.

Each brush holder 420 comprises two lugs 422, each lug 422 extending from a wall 423 of the brush holder towards the outside of the brush holder in a plane offset with respect to the position of the carbon brush.

Each lug 422 is laminated in an insulating layer, not shown, thus enabling the brush holder 420 to be fastened to the support 410 in a non-removable manner. While lamination is taking place, care is taken to avoid any contact between the lugs and the bus bar 411, thereby avoiding creating a path for the current collected from the rotor 404 to pass through in addition to through the flexible member 440.

Alternatively, in an embodiment not shown, the apertures of the lugs 422 may be used for example to fasten these lugs by screwing against an insert covering the wall of the corresponding aperture, as in the embodiment of fig. 3A.

Connection means, such as an electrical connection rod 441, passing through an insulating layer, not shown, and in contact with the conductive plate 411, makes it possible to ensure the passage of electric current from the flexible member 440 toward the conductive plate 411.

The electrical connection rod 441 may have a shape known per se. For example, the rod may include a threaded rod, a nut, not shown, and optionally a support 442: the terminal of the end of the flexible member 440 may be inserted around the rod and pressed between the nut and the support 442 (or between the nut and the insulation layer).

A current sensor 460 is mounted near rod 441.

The current sensor may be embedded in a layer of insulating material, not shown.

The sensor can measure the intensity of the current through the flexible element or rod 441, that is to say the intensity of the total amount of current collected by the carbon brush, due to the insulation performed against the carbon brush.

In the embodiment of fig. 5, the support, which is in the shape of a plate 610 as a whole, includes a bus bar 611 coated with an insulating layer 612.

The carbon brush 630 is received in a brush holder 620 comprising a spring means, not shown, for urging the carbon brush 630 into contact against the rotary element 604.

Although only one 604 is shown here, several rotating elements are provided, separated from each other by insulating discs, one 680 of which is shown.

In this embodiment, the brush holder 620 is made of two parts 621, 622, which can be assembled to each other in a reversible manner.

More precisely, the brush holder 620 comprises a removable portion 621 and an adapter portion 622, the removable portion 621 comprising a cage intended to receive the carbon brush 630, the adapter portion 622 being non-removably fastened to the support 610.

For example, the removable portion may include a spring device that applies pressure to urge the carbon brush 630 into contact against the rotating element 604.

For example, the connection of the not-shown flexible member, one end of which is in contact with the carbon brush 630, to the conductive plate may be performed by a connection device mounted on the brush holder.

This connection means (e.g. a rod system), not shown, may be mounted on the adapter portion 622 and pass through the insulating layer 612 until it is in contact with the bus bar 611.

The connection means may be screwed, clamped or otherwise connected to the adapter portion 622, for example.

Advantageously, a plug-set system may be provided which enables the carbon brushes to be connected/disconnected when the machine is loaded, in particular in the case of synchronous generators for hydroelectric power plants.

Referring to fig. 6A, 6B and 6C, the support 710, 710', 710 "is shown as seen from the side opposite to the side corresponding to the face on which the brush holder is mounted. Therefore, the brush holder is not visible in these figures.

The supports 710, 710', 710 "may define apertures 763, 763', 763", the edges and inner walls of which may be covered with insulating material for the passage of wires connected to sensors mounted on the face of the support on which the brush holder is mounted. For example, a gasket made of an insulating material may be provided that is received in the aperture.

The flexible channel may also be arranged directly in the insulating material.

These sensors on the brush holder side may for example comprise temperature sensors, for example sensors measuring the temperature in the insulating material layer of the coated bus bar.

The temperature of the brush holder can be estimated from the values measured by these sensors and from the thermal conductivity values stored in the database.

Reference numerals 761, 761', 761 "denote sensors mounted on the opposite face to the face supporting the brush holder, and therefore visible in these figures, for example current sensors mounted around a connecting rod ensuring the transfer of the collected current.

Thus, it is advantageous to mount the sensor on a relatively clean face opposite to the face supporting the brush holder, which may facilitate maintenance.

The conductive linear elements 762, 762', 762 "(here flexible, e.g. of the strip type (762, 762')) are connected to the sensors 761, 761', 761" and to the sensors on the non-visible face, thus passing through the apertures 763, 763', 763 "simultaneously.

The conductive linear elements 762, 762', 762 "can be embedded in the insulating material coating the bus bars.

In the embodiment of fig. 6A, a flexible printed circuit 764 or PCB (representing a printed circuit board) is provided that is laminated in an insulating material coating both sides of the bus bar.

Advantageously, at least one sensor is provided on the same face as at least one processing element (processor or other), thus enabling to avoid penetrating the conductive plate.

This may enable a better distribution of field lines, which limits heat generation. Furthermore, this may enable a better creepage distance.

Thus, the component is embedded in an insulating material such as PEN.

In the embodiment of fig. 6B, a rigid card PCB is provided that is received in a housing 764' that is soldered or screwed to the bus bar.

The conductive linear element 762' is flexible (tape).

In the embodiment of fig. 6C, the conductive linear element is a conventional wire or flexible piece, also embedded in the insulating material. Slots may be provided in the support to receive these wires 762".

These wires 762 "are connected to a printed circuit received in a housing 765 mounted on an insulating layer, for example via screws.

In all cases, a CAN (stands for "controller area network") bus type connection may be further provided.

Claims

1. A current transfer system between a rotating element and a stationary element, in an asynchronous rotating electric machine or in a synchronous electric machine for power transfer, or also in a transfer system that can be used for grounding, the rotating element being moved in a rotational movement with respect to the stationary element, the transfer system comprising

A support (10) having an overall shape of a plate, comprising, on the periphery of the rotation axis of the rotating element, a conductive portion (11) electrically connected to one of the fixed element and the rotating element,

at least one brush holder (20) mounted on and supported by or integrated into the support (10) and shaped to hold at least one conductive sliding contact element (30),

said conductive sliding contact element (30) supported by said brush holder and intended to be pushed into contact against the other of said fixed element and said rotating element,

A resistive element located between the conductive sliding contact element and the conductive portion of the support when the conductive sliding contact element is urged into contact to limit the passage of current directly between the conductive portion and the conductive sliding contact element,

2. A system according to claim 1, wherein the resistive element comprises an insulating element between the conductive sliding contact element (30) and the conductive portion (11) of the support (10) when the conductive sliding contact element is supported by the brush holder and urged into contact, and the system is shaped such that the insulating element thus prevents the passage of current directly between the conductive portion and the conductive sliding contact element.

3. The system according to claim 1 or 2, further comprising at least one sensor (460; 761') capable of measuring a parameter value representative of the operation of the conductive sliding contact element (430).

4. The system of claim 3, further comprising at least two conductive linear elements (762; 762 ') electrically connecting the sensor (460; 761') to a processing device (764; 765) for exchanging measurement or control signals,

characterized in that the conductive linear elements are at least partially embedded in a resistive or insulating material.

5. The system according to any one of claims 3 to 4, further comprising processing means (764; 765) in communication with the ventilation device and with the sensor (460; 761';761 "),

characterized in that the processing means are arranged to control the ventilation device in dependence of measured values from the sensor.

6. The system according to any one of claims 1 to 5, wherein the conductive portion comprises a bus bar type conductive plate (11; 411;511; 611).

7. The system according to claim 6, wherein the resistive element (12) is obtained by applying a resistive material having a resistivity of at least 0.1 ohm-meter onto the conductive plate (11).

8. The system of claim 7, wherein the brush holder (420) defines at least one tab (422) extending from a wall of the brush holder toward an exterior of the brush holder in a plane closer to the support than a position of the carbon brush (30), the position being defined by the wall of the brush holder, and wherein the tab is laminated in the resistive or insulating material.

9. The system according to claim 7 or 8, wherein the resistive element (512; 612) is obtained by coating and/or over-moulding the conductive plate (511; 611) with the resistive material.

10. The system according to any one of claim 1 to 9,

characterized in that at least a portion (420; 622) of the brush holder is fastened to the support (410; 610) in a non-removable manner.

11. The system according to any one of claims 1 to 10, wherein the brush holder (20; 420) is made of a single sheet metal.

12. An assembly comprising a rotating element (404), a stationary element and a transfer system according to any of claims 1 to 11.

13. Use of the assembly according to claim 12 in industry or in wind power industry.

14. A method for manufacturing a current transfer system between a rotating element and a stationary element, the current transfer system being in an asynchronous rotating electrical machine or in a synchronous electrical machine for power transfer or also in a transfer system that can be used for grounding, the rotating element being moved in a rotational movement relative to the stationary element, the method comprising:

providing a support having an overall shape of a plate, said support being intended to be located on the periphery of the rotation axis of said rotating element, said support comprising a conductive portion intended to be electrically connected to one of said fixed element and said rotating element,

Providing at least one brush holder mounted on or integrated into the support, the brush holder being shaped to hold a conductive sliding contact element,

installing in the brush holder the conductive sliding contact element intended to be pushed into contact against the other of the stationary element or the rotating element,

providing a resistive element between the conductive sliding contact element and the conductive portion of the support when the conductive sliding contact element is urged into contact,

-providing electrical connection means for electrically connecting the conductive portion to a flexible member rigidly connected to the conductive sliding contact element for conducting an electrical current between the conductive plate and the conductive sliding contact element.

15. The method of claim 14, further comprising

A resistive material is applied to the conductive portion and/or the brush holder to form the resistive element.